FI123381B - Method of improving a wood material - Google Patents

Description

METHOD FOR IMPROVING WOOD MATERIAL

The invention relates to a process for making a synthetic polymer-containing wood, wherein a liquid containing a polymerizable substance is impregnated into the wood block and the polymerizable substance is polymerized by keeping the impregnated wood block between the temperature-controlling surfaces in a closed space.

The technical use of many wood species is limited by their natural softness. The softness of the wood material, like its other mechanical strength properties, is due to the microstructure of the wood. This is very different for different wood species. All types of wood consist mainly of run-hollow hollow cells, that is, wood fibers of varying size and texture! n. The larger the cellular cavities of the wood relative to the cell size, the softer and weaker the wood can be. Due to their biological origin, the wood surface is also vulnerable to fouling, wear and damage caused by microorganisms, especially in humid conditions and changing weather conditions. In addition, the use of wood materials is reduced by the flammability of the material.

The permeability, i.e. fluid permeability, of different wood species, and also of different parts of the same wood species, surface and heartwood, and spring and summer wood, is such that the handling of the material and its uniform hardness and other properties are difficult or even impossible to achieve. The anisotropic structure of wood thus plays an important role in the suitability of the product, for example, as a surface material for floor coverings. Anisotropic structure refers to various structural and strength properties of wood in radial, tangential and longitudinal directions. Wood material is often worked at random so that the surface direction of the products is often the same as the tangent of the annual rings. In this case, relatively large areas of poorly saturated soft spring wood and highly saturated summer wood are present on the surface. This problem is widespread when impregnating conifers, whose thin-leaved hardwood cells are generally less saturated than the harder hardwoods already.

One of the most important properties related to the use of wood materials is its durability both indoors and outdoors. Being a natural polymer, wood is degraded by many biological organisms and pests, mainly fungi, microbes and insects. Decay refers to the complete or partial decomposition of 2 wood by fungi and / or microbes. Decaying fungi are the worst decomposers and destroyers of unprotected trees, as they contain decaying agents for all the structural components of the wood. As a result, the appearance and structure of the wood surface are altered and its properties reduced.

In addition, the wood material is exposed to various climatic conditions such as heat, humidity, water, pollution and both visible and UV light. For example, light causes the wood surface to turn yellow and darken even in indoor applications. However, this yellowing and darkening of the surface may be the result of at least three reasons. First and foremost indoors, the discoloration is due to the oxidation of wood-containing substances in the absence of organisms. The most sensitive of the basic components of wood is UV lignin, which is estimated to be responsible for 80-95% of the light absorbed in wood. The other two possibilities are related to the action of decomposing organisms and microbes that alter the structure of the wood. Fungi are more harmful to living trees than to wood, as they mainly cause discoloration because they utilize water-soluble extracts of wood, starch and sugar. However, the worst wood destroyer is the combined effect of all of the above.

The fire resistance of wood material is also limiting its wider use in the interior. Many products require a certain level of fire protection before being approved for use. Such uses include so-called public spaces such as hotels, hospitals, theaters, museums, public offices, etc. In these applications, for example, the use of wooden flooring is very limited. In the polymerization of wood materials, flame retardants require high decomposition temperature, low volatility, non-existent influence on the mechanical properties of the polymers, good UV radiation resistance and non-toxicity. In processing, they do not form toxic gases when decomposed and the end product is non-toxic.

There is a problem with polymerization, i.e. solidification of substances within wood material. How can the polymerization be carried out in such a way that the void space is filled as evenly as possible without affecting the material properties? Polymerization is often hindered by the use of higher molecular weight oligomers, prepolymers or polymers which tend to run out of wood material during polymerization. The surface portions of Finnish birch and pine, for example, are particularly difficult to impregnate with high molecular weight substances.

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When using small molecule compounds, i.e. monomers, other problems are encountered during the polymerization step. The greatest of these is the volatility of the compounds during polymerization. This results in major financial losses, product degradation, occupational safety and environmental problems. Evaporation may be about 50% of the compounds absorbed into the wood material during different solution treatments and during the impregnation and polymerization process, up to 90% in the open system.

Often, during polymerization, the material burns, changes its coloring, cracks or otherwise loses its general technical properties. For example, important application properties of wood materials are woody appearance, uniformity of strength property, workability, sandability, bonding and surface finish. One of the important handling issues is not to forget about the disposal of the material.

Substances used to impregnate materials are often polymerized by heat, radiation or light. The polymerization reaction is an exothermic process. For example, wood-based materials often cause cracking, discoloration, dimensional changes, and burning. The temperature in the exothermic reaction rises very high. Methods already known have tried to prevent this by openly polymerizing the material between the hot plates, cf. Patent Publication FI-44946. The hot plates act as initiators and coolers of the reaction. A disadvantage of the method is to control the internal uniformity of the reaction, especially with thick and permeable materials. This results in loss of uniformity of properties, cracking and color differences, and a great loss due to evaporation of the materials used in the polymerization. The method is thus expensive in terms of production costs as well as occupational safety.

One way to control polymerization reactions is to use radiation to initiate polymerization. Attempts have been made to prevent the evaporation of chemicals by, for example, adding rapidly gelling divinyl compounds to the monomers. By using addition polymers, the material can then be treated by irradiation methods such as gamma irradiation or electron bombardment. Using the method on a factory scale is expensive in terms of equipment and operating costs, and designing it for wood materials, especially thin sheet products and veneer materials, requires high equipment and cost. Furthermore, the use of radiation significantly increases occupational safety risks and is thus an environmental risk.

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There is also a method, cf. No. 44945, in which wood containing synthetic polymer is prepared by means of a catalyst and heat, whereby the polymerization reaction is retarded by conjugated unsaturated fatty acids, terpenes with three double bonds or derivatives thereof. The disadvantage of using such retarders is that they may react differently with different materials.

The method has also been used, cf. Fl-94607, in which the material is heated with various polymerizable materials in a closed system with hot water. A disadvantage of the method is its application to wood materials, in particular to board-like products and veneer materials. In addition, due to the different water absorption of wood materials, post-process drying of the materials causes problems with the performance properties of the materials. The materials crack, alter their dimensions, their coloration and thus their appearance while diminishing their strength properties. As a result, the said. the process requires large and expensive process equipment in the after-treatment, and the waste of products increases, making the products less economically viable.

Methods have also been used in which files are heated with filing gases and water vapor to initiate and cool the reaction, cf. Fl Patent 500070. When using flowing gases, a lot of harmful evaporation of gases and chemicals is produced. This causes uneven curing and appearance problems. Gas recovery systems are expensive and together they increase the cost of the process and reduce its profitability. In addition, evaporation causes occupational safety and health problems. When steam is used, impurities, deposits and extrudates are formed on the surfaces of process equipment and products. These cause cleaning problems, process malfunctions, removal problems, and a great deal of waste in product finishing as the product dimensions and appearance change.

Methods of treating impregnated bodies with heat transfer paths have also been used. DE-A-1792051 discloses the use of glycol as a heat transfer fluid. SE 405329 uses polyethylene glycol. The methods cause post-treatment problems for the treated products, eg during gluing and surface treatment. Glycol residues prevent, for example, the adhesion of lacquers to the adhesive and application surfaces of products. The use of emulsifiers reduces the thermal conductivity. There is the risk of unevenly cured products and the risk of the process overheating. Overheating causes deviations in product dimensions, cracking, burning and discoloration. Process control is made more difficult by uneven curing 5, whereby the impurities created impede the operation of the process equipment and increase the need for cleaning. Slow process extrudates on the various surfaces of the products complicate the finishing of the products, increase wastage and thus make the process economically less profitable.

The purpose of the present method is to eliminate the above-mentioned disadvantages and to provide as simple, environmentally friendly, safe and cost-effective method as possible for improving the properties of wood materials, for example, hardness. As mentioned above, the invention relates to a process for the production of wood containing synthetic polymer, wherein the wood body is impregnated with a liquid containing the polymerizable material and the polymerizable material is polymerized by keeping the impregnated wood body between the temperature controlling surfaces in a closed space. The invention is mainly characterized in that the wood body impregnated during the polymerization is kept under excess pressure. In the pressurized system of the invention, conditions such as polymerization temperature and retention of polymerizable materials in the wood can thus be controlled while providing and controlling an exothermic polymerization reaction by means of temperature controlling surfaces and a closed space.

According to one embodiment, the overpressure is achieved by placing the impregnated wood, preferably with temperature adjusting surfaces, in a dense space and raising the temperature of the space and / or supplying a medium thereto. The sealed space is achieved, for example, by placing a sealed barrier, the material of which is selected, for example, from metal, rubber, wood, glass, plastic or a combination thereof, between the heat-adjusting surfaces outside the wooden body. The dense space can also surround the wood piece and the temperature controlling surfaces.

For example, pressure reduction in a tight space is achieved by allowing unnecessary overpressure to escape from the closed system by means of overpressure or emergency valves. During polymerization, the overpressure of the dense space is most preferably achieved by means of an inert gas. This is the case, for example, with nitrogen gas. At the same time, the gas inhibits the polymerization reaction during the polymerization process without adversely affecting the oxygen.

Preferably, the overpressure is maintained at such a high level that it prevents the liquid or gas formed by it from escaping from the impregnated wood block, most preferably greater than the vapor pressure of the liquid used and / or its essential components. Typically, pressures greater than 6 are maintained at 200-500 kPa (2-5 bar), most preferably 300-400 kPa (3 -4 bar). As the exothermic polymerization tends to increase the overpressure, it can be limited or reduced by means of a discharge valve connected to the tight space. By reducing the overpressure, the heat produced by the exothermic polymerization is also eliminated.

Applications of wood materials with the most pronounced material hardness properties, fire resistance and appearance are building materials surface materials, such as floor coverings, mechanical forest board products such as plywood, particle board, OSB, multi-ply and multi-ply, and various composite boards. and table tops. Applications where material properties also require weather, biological and mechanical resistance include outdoor products such as garden furniture, underwater and mine support materials, wall façade materials and train tracks. Design objects can also utilize deep or partial dyeing of materials.

The wood material used may be any wood material, but soft wood materials such as hardwood hardwoods and softwoods are less commercially utilized in terms of wood material properties such as hardness.

When the absorbency of wood is the decisive criterion, the material of the wood body is preferably selected from the following species; red oak, beech, Douglas fir, red cedar, ponderos pine, birch, white spruce, larch, alder, hemlock, pine (surface), English spruce and maple.

Among Finnish wood species, birch, aspen, alder and pine, as well as about a hundred foreign species, due to their hardness properties, compete evenly with the most well-known hard wood species such as cherry, ash, beech and oak.

It is important to choose the right working method for the wood material (sawing, cutting or turning). Namely, the invention utilizes the strength and saturation properties resulting from the inhomogeneity of wood. For example, when the product is applied to a floor covering surface, the surface structure is machined in the direction of the body for surface inhomogeneity and mounted on the product surface such that the radial side most favorable to the hardness and surface homogeneity is the product surface. In this case, the annular rings of both the summer and spring trees of the 7 annual tumors are almost perpendicular to the surface. The surface thus exhibits a sturdy, hardwood and softer springwood cell in the form of dense stripes.

The anisotropic properties of wood materials and their best qualities can be utilized by performing the work of wood material by the best methods of cutting, turning or sawing. The direction of machining also affects the absorption and thus the properties of the product. It is advantageous to work the piece of wood so that the number of annual rings visible on its surface is as high as possible (positioning the beam in a direction parallel to the surface, fostering the right economic machining direction for each species of wood). Prior to impregnation, the piece of wood or its raw wood may be pretreated by partially disrupting its cellular structure, preferably by penetration by a spike, knife or laser.

The appearance of wood material can also be influenced by proper pre-treatment. The wood material can be aligned to the process by preheating the material to a suitable working temperature by known methods. Known methods include hot water, steam, hot gases, etc. By controlling the incubation temperature and time, the best possible processing quality is also achieved. Experimentally, it has been shown that temperatures of 80 to 90 ° C can be best used as hatching temperatures for round wood and hatching times of 10 to 30 hours at hatching times. However, wood material usually requires preheating the material for about 8 hours in water at about 60 ° C. The deciduous trees achieve a usable color tone suitable for a method such as the invention, such that a darker uniform tone is produced at 88 ° C and 20-30 hours incubation, a lighter uniform tone is produced again at about 80 ° C and a 15-30 hour incubation. Applying the times and temperatures with the above process values, there is no color difference between the surface portion and the core portion of the wood material. However, the temperature required for the wood material and the time necessary for incubation are dependent on the quality of the wood, which is mainly influenced by e.g. place, age and date of felling.

The pre-treatment by heating is generally carried out preferably by keeping the piece of wood or its raw wood at an elevated temperature of 70-100 ° C, preferably at the temperature of 80-90 ° C mentioned above. The pre-treatment time is preferably about 15-30 hours, most preferably about 10-15 hours.

The hardness of the wood and its general properties can be affected by filling the cellular tissues and voids of the cell walls as homogeneously as possible with substances which can be solidified to δ. Other material voids are filled with the above materials. The filling can be accomplished by impregnating the material in a confined space with liquids that can be polymerized inside the material. The problem with wood materials is to make the liquid substances penetrate as homogeneously as possible into the material. For wood materials, the permeability of liquids, i.e., permeability, varies greatly between different wood species between the site, the cut, the age and the different parts of the wood material. As a result, wood-less permeable wood species are often impregnated with a liquid containing polymerizable material by means of vacuum and / or overpressure. The invention allows the amount of absorption to be individually regulated for each wood species and product. By doing this, sufficient wood properties can be achieved while saving on the use of expensive chemicals. The invention typically utilizes an autoclave, impregnation cylinder, or impregnation tank scale for controlling weight and absorption rates. For the treatment of wood species and wood product combinations during impregnation, an appropriate prescription for each product is used. Doing so can save useless features and costly additives.

Preferably, the liquid containing the polymerizable material is impregnated into the wood body by means of vacuum and / or pressure. In this case, absorption is typically accomplished by evacuating the wood block and absorbing the liquid therein at normal pressure or by supplying the liquid with excess pressure. The amount of impregnation of the various wood species suitable for impregnation may range from 50 to 500 kg / m3. Depending on the end product, the above hardness limit and the economic process, the amounts of material are preferably 50-500 kg / m 3.

In the process of the invention, the polymerizable material may be absorbed into the wood material as such, in the form of a solution, dispersion or other mixture. The main point is that the polymerizable material and the material to be treated are liquid permeable / absorbent. Advantageously, the absorption takes place in a shielding gas, most preferably in an inert gas. If necessary, the viscosity of the liquid containing the polymerizable substance may be adjusted with an additive.

According to one embodiment, the liquid containing the polymerizable agent contains a wood additive selected from antimicrobial agents, fire retardants and colorants.

In order to improve the fire resistance of the wood material material, various gas phase flame retardants, solid phase mechanism, physical mode of action or chemical mode of action may be used. The efficacy of the gas phase agents is based on the effect on the polymer combustion chain already during thermal decomposition. Flame retardants form radical traps that break the combustion chain prior to the exothermic reaction of the radicals with oxygen. The reaction products thus remain in the surface layer of the wood material, preventing combustion.

1) By the solid phase mechanism, the flame retardant acts by chemical interaction between the flame retardant and the polymer, often by crosslinking the molecular structure. Interaction occurs below the thermal decomposition temperature of the polymer. Crosslinking increases covalent bonds and thus slows down pyrolysis.

2) In the physical mode of action, flame retardants are physically active in both gaseous and solid phases. In the gas phase, the thermal capacity of the flame retardant molecules, the evaporation energy and the degradation of the endothermic structure are important. In the solid phase, certain acids generate a carbonizing surface, releasing water vapor into the gas phase. Water vapors quench combustible gases. When charring is an endothermic reaction, it cools the wood material and slows down the thermal decomposition. The flame retardant also forms a solid film on the surface of the material which prevents the volatile gases from evaporating.

3) In the chemical mode of operation, flame retardants work chemically in both gaseous and solid phases. In the gas phase, they break the fire chain by binding the free hydrogen atoms and preventing them from reacting with the oxygen molecules. In the solid phase, the acids of the flame retardants catalyze the dehydration which causes carbonization. The flame retardant can also control the thermal decomposition so that no fuel is generated on the flame as the decomposition product.

Flame retardants are various metal compounds or organohalogen compounds. There are about 350 of these, in addition to compounds and combinations of substances, for example, aluminum hydroxide (ATH), functional flame retardants that can be polymerized as part of the polymer chain of plastics. Their durability is improved and the material becomes more uniform. Good results have been achieved with the so-called blocked amines (NOR-hindered amines), which sequentially contain nitrogen N, oxygen O and radical group R. The benefits of functional flame retardants are already achieved at low concentrations and do not affect the mechanical properties of the final product. Phosphorous based flame retardants work in either solid or gaseous phases both chemically and physically. These include phosphine oxide and ammonium polyphosphate in the solid phase and triphenylphosphate and triphenylphosphine oxide in the gas phase.

Organic or synthetic organic dyes may be used to dye wood materials. Organic natural dyes are composed of carbon compounds. Dyes may be derived from nature, either from the animal or vegetable world. Organic full pigments are pigments that are throughout the color. The organic substrate pigments, in turn, are obtained by mixing a water-soluble dye with a solid, inert substance (e.g., clay) to obtain a solid color.

Organic natural dyes include: sepia and indian yellow. The most common naturally occurring chromophores are quinone, methylene quinone, oxazone, lactone, azo group and carbonyl group. Synthetic organic materials consist of laboratory-produced carbon compounds that do not exist naturally in nature. The earliest synthetic dyes were made from coal tar and had poor light resistance. Nowadays, pigments derived from petrochemicals are used for coloring - the pigments are made from crude oil and the main components are benzene, toluene, xylene, naphthalene and ethylene.

The various chemical classes include monoazo, diazo, phthalocyan, quinacridone and polycyclic pigments. Further, various classes include pigment dyes, reaction dyes, acid dyes, vat dyes, sulfur dyes, dispersion dyes, straight dyes, cationic dyes, naphthol dyes. Azo compounds are compounds in which two nitrogen atoms form an azo group. The azo dyes are divided into mono, dis and polyazo compounds. The azo dyes can be grouped e.g. monoazoles (naphthols, arylides (acetoarylides and naphthanilides]), azocondensation dyes, insoluble salts of acid dyes, diazo dyes (diarylics, pyrazolone dyes). , arylides [acetoarylides and naphthanilides]), azocondensation dyes, insoluble salts of acid dyes, disazole dyes (diaryls, pyrazolone dyes).

The biological resistance of wood material can be improved by antimicrobial agents, but the interaction between the resulting polymer and the above compounds is usually sufficiently antimicrobial.

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The liquid containing the polymerizable material may contain an organic, water-insoluble solvent which promotes the dissolution and reaction of the monomers and / or prepolymers.

The polymerizable substance can be, in principle, any substance that polymerizes or cross-links into a polymer product within the wood material. The polymerizable agent is typically selected from the group consisting of polymer forming monomers, oligomers, prepolymers, or a mixture, either external or external.

The polymerizable agent may be selected from the group of thermosetting plastics which includes acrylic monomers such as acrylic and methacrylic acids, acrylic and methacrylic esters, acrylonitrile and vinyl amides, styrene monomers such as styrene, α-methylstyrene and divinyl benzamide, , aldehyde monomers such as formaldehyde and acetaldehyde, polyalkylene oxides such as polyethylene oxide and polypropylene oxide, and ring lactams and lactones. The preferred polymerizable material here is an acrylic, styrene or vinyl polymer.

The polymerizable material may also be selected from the group of thermoplastic prepolymers which include phenol, urea, and melamine formaldehyde products, polyurethanes, epoxides, silicones, and unsaturated polyesters. Most preferably, the polymerizable material is selected from the group consisting of a curable mixture of an unsaturated polyester and a styrene or acrylic monomer.

If it is desirable to cure or modify and improve the appearance, processing, weathering or strength properties of the wood material after curing, it is preferred to add a crosslinking agent to the polymerizing agent by polymerizing the impregnated material. This may be a common monomer which forms a chain between prepolymers or a multifunctional monomer which, when acting as a monomer, further reacts and attaches the polymer chains to one another.

Most preferably, the polymerization is carried out using a catalyst or an initiator. When unsaturated monomers and / or prepolymers are used, polymerontal initiates what is known as initiation. The initiators are the free-radical generator, the anion-generating anionic initiator, or the cation-generating cationic initiator. The most important of these is the radical initiator.

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Typical radical initiators include peroxides such as diacyl peroxides, acetylalkydisulfonyl peroxides, diacyl peroxide carbonates, tert-alkyl peroxide esters, O-tert-alkyl-O-alkyl monoperoxydicarboxylates, di- .1-alkyl hydroxides, ketone peroxides, and silyl peroxides. The peroxides which decompose into initiating radicals in the polymerization are listed above according to a decreasing tendency for degradation. Typical peroxides include di-n-propyl peroxide carbonate, dilauroyl peroxide, diacetyl peroxide, dibenzoyl peroxide, dicumyl peroxide and di-tert-butyl peroxide.

Other radical initiators include azotype initiations such as 2,2'-azobis - ((2,4-dimethyl)) pentanenitrile, 2,2'-azobis-isobutyronitrile and 1- (tert.amylazo) cyclohexane carbonitrile.

The invention may also employ the so-called. photoinitiators which, upon exposure to light, decompose into polymerisation initiating radicals.

When the wood material is impregnated with polymerizable and partially non-polymerizable materials, the impregnated and polymerizable material is protected prior to the polymerization process with a material which prevents the polymerizable materials from adhering to the process equipment while preventing material from being post-treated. Such materials include, for example, various coated metal glass, wood or rubber sheets or various treated papers or fabrics.

The polymerizable material is typically polymerized by keeping the impregnated wood body at a temperature high enough to effect polymerization but below the decomposition temperature of the wood body material. In one embodiment, the polymerization temperature is maintained between 40 and 200 ° C, preferably between 100 and 200 ° C. The polymerization temperature may be limited by the use of a slowly decomposing initiator and / or a polymerization retarder.

As mentioned above, the polymerizable material is polymerized by keeping the impregnated wood body under pressure between the heat-adjusting surfaces. It is preferable to keep the impregnated piece of wood in the same overpressure medium and press between the temperature adjusting surfaces. The surfaces then act as a regulator of the correct polymerization temperature so that the polymerization proceeds without decomposing the wood material. The temperature adjusting surfaces substantially conform to the surfaces of the wood block and are preferably flat.

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The polymerization process is exothermic and can cause overheating, which damages both the polymer and the wood material to be treated. The overheating caused by the polymerization reaction is preferably prevented by cooling and controlling the pressure on the temperature controlling surfaces between which the wood material is sealed.

Typically, the polymerizable material is polymerized by holding the impregnated block of wood between the temperature-controlling surfaces which are the surfaces of the elements made of heat-conductive material. According to one functional embodiment, the elements are made of a heat-conductive material such as metal. The elements are typically provided with channels for supplying a heat adjusting medium such as oil or water.

Thereby, a heating medium is introduced into the ducts of the elements at the beginning of the polymerization to initiate the reaction, and in the exothermic phase of the polymerization a cooling medium to prevent the monomer from boiling and / or destroying the wood material. The heating medium is then used to maintain the temperature of the heat-adjusting surfaces between 40 and 200 ° C, preferably between 100 and 200 ° C.

It is also advantageous to regulate the amounts of material according to sufficient properties of each material. The pressure of an inert gas, such as nitrogen, must be controlled so that the polymerizable material and the water remaining in the material, such as wood, do not boil. temperature.

When the polymerization process is completed, any pressure applied to create excess pressure is removed and the wood material is transferred to the next process step. The removal of overpressure is carried out in a controlled manner so that releasing the pressure does not cause any qualitative problems for the wood material. This is done so that after the correct process time, the pressure of the polymerized material is slowly lowered before the press plates open and transferred to the next process step.

The process equipment is cleaned by brushing, blowing or otherwise mechanically contaminated. Plastic bursts and other impurities that may be generated by such a procedure are removed from the surface of the polymerization apparatus. The actuators are clean for subsequent polymerization. Liquid chemicals that have left the process are collected in collection vessels and returned to the impregnation process.

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Once the actual polymerization process has been completed, it is advantageous to carry out a so-called post-polymerization process on the polymerization product in the wood material. The purpose of this is to minimize the amount of material-bound emissions and to cool the products before further processing. The post-polymerization is preferably accomplished by heat.

Thanks to the above invention, the wood material retains its shape well, the hardness becomes much more uniform, and new types of hard-to-saturate wood can be utilized as products of a higher degree of processing. No separate finishing is required due to the different substances and additives used to modify the product or used in the process. The evaporation of chemicals is minimized. The equipment is suitable for manufacturing plate-like and smaller products, and the equipment used in the production process is standard equipment. The process is work-safe and can provide significant cost savings over open systems.

The best results from the polymerization and various properties of wood materials are achieved through the most homogeneous impregnation and a well-controlled polymerization process. As stated earlier, the non-homogeneous structure of the wood material makes it difficult to obtain the best results. In terms of impregnation, knowledge of different types of wood, orthodontic pre-treatment, machining, selection of the right blends of materials and a controlled impregnation program are key to the end result.

Knowledge of different types of wood makes it easier to understand the internal structural differences of the same wood type and to select only the right areas for processing. Controlled pre-treatment of wood material again reveals the qualities that best serve the processing and appearance of the wood species.

The key elements in the impregnation process are the impregnation head used, knowledge of the permeability of the wood species in the various components, pressure, time of pressure treatment, amount of impregnation required and monitoring of the correct impregnation rate.

In polymerization, control of the correct polymerization conditions is key. Minimizing the cost of expensive impregnating agents is essential for economy and competitiveness. This means controlling a closed system from a technical point of view. The desired polymerization is achieved in a closed system at the correct wood species specific polymerization temperature and time.

Different wood species and their intrinsic permeability differences affect the amount of impregnating agents. In addition, the desired quality of the final product requires the correct absorption adjustment. Different wood species get bored in different ways. Worldwide wood species (eg Industrial Timber Preservation from 1979/391 different wood species) can be distinguished from woods that are highly liquid permeable in terms of saturation and handling (17%), wood species that are generally or frequently resistant to fluid permeability (17%), and unsaturated wood species (43%). The natural hardness of wood species, on the other hand, can be estimated as follows: Very hard wood species (16%), Hard wood species (18%), Generally hard wood species (19%), Non-hardwood species (26%) and Fragile wood species (21%).

From the point of view of saturation and polymerization, both the starting properties of the wood material and the additional properties obtained by impregnation and polymerization must be taken into account. It is not economically viable to deal with wood species that are already hard enough, or wood that absorbs too much material. In terms of hardness, it is generally thought that oak hardness is considered to be a good hardness of the final product. It has a Brinell hardness of about 3 N / mm 2. Harder products are selected for demanding applications and lower hardnesses are used in other mass production.

At least 31% of the 391 wood species mentioned above, or about 86 wood species, can be utilized for demanding and valuable conditions of use in accordance with the invention, provided that the criteria are economic and competitive and at least the hardness of the oak.

In a normal open impregnation and polymerisation process, losses due to evaporation of material amounts can reach up to 90% of the amount absorbed in the wood material. On average, the loss rate is 75-80%. From the point of view of the invention, a closed system can significantly reduce evaporative losses.

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With the impregnation methods commonly used, the absorption rates of the substances N kg / m3 and the polymerization residues B / kg / m3 in open polymerization and the polymerization residues of the closed system C / kg / m3 are, for example, on average: N kg / m3 B / kg / m3% Cl kg / m3% • birch 450-550 100- 130 22-24 250-350 55-64 • alder 450-550 100- 130 22-24 230-340 51 -62 • aspen 550-650 100- 120 18-34 250-350 45- 54 • pine (hardwood) 300 - 450 65- 115 22-26 160 - 250 53 - 56 • beech 250-450 50- 77 17- 20 140-260 56 -58 • red oak 150-325 20- 65 13-20 180 -200 55-62 • cherry 450-550 100- 120 22-34 240-340 53-62 • ash 450-550 100- 120 22-34 230-330 51 -60 • maple 450-550 100- 130 22-24 250-350 56-64 • Larch 150-200 25 - 60 17-30 80- 130 53-65 * • Douglas Spruce 50- 135 10- 20 20- 15 25 - 75 50-56 * • Hemlock 200-400 50-100 25 100-270 50-68 • English spruce 150-270 30- 70 20-26 70-150 47-56 * • red cedar 130-350 20-100 15-22 50-230 3 8-66 * • Ponderos Pine 300-490 50-110 17-22 150-270 50-55 • White Spruce 90-120 20 - 35 22-29 50- 90 56-75 *

Mean% 23.4 56.4

Average, kg / m3 348.6

The range of values for the saturation rates in the table is based on differences in the same tree species. Types of wood marked with an asterisk are often difficult to saturate and have large differences in internal saturation.

As can be seen from the values in the table, the invention improves the polymerization residues by about 2 to 3-fold compared to the open system. Differences in final residue levels result from the inhomogeneous saturation of the various components applicable to the invention of the same 17 species of wood and from various environmental factors.

From an economic point of view, the invention can be considered to save chemical costs by an average of 100 to 200 kg / m 3 compared to open polymerization systems. Production costs are reduced by 25-35%. Thus, the same combination of hardness or other properties is achieved with 25 to 35% less solution volumes. In addition, the invention smoothes out the residues of different species of wood, and the areas of the species that are not homogeneously treated are not so clearly distinguished.

The average chemical consumption of the production is 350 kg / m3 and the cost is 10,000 EUR / m3. With an open polymerization system, the system evaporates an average of 270 kg / m 3, but with a closed polymerization system according to the invention only a maximum of 150 kg / m 3 of the wood species and the properties of the desired product. The same result is achieved with a lower amount of material of 120 kg / m3 and a lower cost of 350 - 800 EUR / m3. In addition, the quality of the products is smoother than in an open polymerization system.

The following is an exemplary embodiment, which is intended only to illustrate the above invention.

Example:

A standard 4 'x 8' birch plywood product with surface veneer / veneers pre-treated to provide even coloration through incubation and microscopic fractures on the surface of the structure and the correct orientation of the surface during plywood bonding. The plywood product is loaded into equipment designed for impregnation.

The plywood product is treated with a solution mixture of 90% acrylic monomer or prepolymer and crosslinking agents about 9-9.5% and catalyst 0.5-1.0%. For successful processing, the weight of the product is continuously measured during processing. If fire protection properties are desired for the product, a flame retardant, for example various water-insoluble compounds, is added at about 1-2%. In addition, if the product to be treated is to be dyed, water-insoluble organic dyes may be added to the impregnation mixture.

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After impregnation, the plywood product is packaged in a special package for polymerization and fed to a hot press. After feeding to the hot press, lateral airtight shields are placed around the press plates for a closed system and the press is lowered. An inert gas is supplied to the closed system for overpressure, bringing the system overpressure to about 300 kPa (3 bar). The temperature of the press is raised to about 120 ° C. As the exothermic polymerization process begins, the internal pressure in the pressurized closed system begins to rise, keeping the pressure level high enough to prevent chemicals from being discharged from the ends of the sheet. If the pressure becomes too high, the safety valve can be used to reduce the pressure.

The curing time varies depending on the thickness and size of the material to be treated and the amount of material introduced. After only the surface layer of the plywood product has been treated and as short as possible from the side and end directions of the plywood, the polymerization process can be interrupted after about 20-30 minutes.

The press plates and side shields are raised and the composite product is fed into a post-treatment process. The press surfaces are cleaned and a new batch is fed to the press for polymerization. During post-treatment, for example, the plywood is kept at a temperature of + 50 ° C for 3-4 hours, after which the plywood is ready for further processing.

The end result of the method is a product having hardness values of 5 to 10 times that of a normal equivalent wood species, and of up to 10 to 20 times that of a high permeability wood species. The Brinell hardness value is often used for comparing the hardness of wood and, for example, in the flooring industry, the hardness of the oak is about 3.0 N / mm 2. Normal birch has a Brinell hardness of about 2.0 - 2.6 N / mm2 and after treatment according to the method, a hardness of Finnish pine of about 1.0 - 25 N / mm2, up to 50 N / mm2, 7 N / mm2 and after treatment 3.5-7.0 N / mm2, the hardness of the Finnish wound is about 1.3-1.4 N / mm2 and the hardness of the treatment is 8.0-13.0 N / mm2 and algae hardness is about 1.2-1.3 N / mm2 and the processing hardness is 5.0 -10.0 N / mm2. Among the foreign species, beech beech, which has a Brinell hardness of about 2.6 to 3.3 N / mm2 and after treatment 6.0 to 9.0 N / mm2, the hardness of red oak before treatment is about 3.0 N / mm2 and treated from about 7.0 to about 10.0 N / mm 2, hardness of hemlock from about 1.2 to about 1.3 N / mm 2, and from about 7.0 to 9.0 N / mm 2, hardness of Douglas fir is about 1, 15-1.40 N / mm 2 and 3.5 to 4.0 N / mm 2 when treated and a hardness of basswood of about 1.26 N / mm 2 19 and a hardness of 8.0 to 10.0 N / mm 2. Dispersion of hardness values of wood is due to the natural inhomogeneity of wood material and different permeability of liquids, for example between wood surface and core.

The product produced by the process retains well the natural beauty of the wood, substantially improves the wear resistance of the product, smoothes its expansion and decreases its length expansion, greatly improves the abrasion properties of the product, can be sanded, machined, glued and fire resistance suitable for L-class public properties, improved water resistance properties of the product (substantially reduced water absorption rate and speed, increased product stability and improved isotropic and homogeneous surface moisture minimization), product can be colored either as deep or partial discoloration natural structure, improved biological resistance of the product, thermal conductivity of the product (phys.); thermal conductivity (chem.) improves, product strength increases (flexural stiffness, flexural strength, flexural fracture, torsional stiffness and torsional strength, impact strength, impact resistance, impact resistance, impact resistance, and resistance to compression).

In addition, the process is well suited for the production of veneers, lamellas, solid wood and round wood products, as well as for the manufacture of sheet-like products such as plywood, OSB, particle board, MDF, solid monolayer or multilayer boards, etc. The method is suitable for weather, light, fire or biological protection of sheet products such as plywood surfaces and ends. The method is suitable for weather, light, fire or biological protection of solid wood surfaces or ends. The method can be utilized in the manufacture of composite products and product development. Applications include the stone industry, the automotive industry, the plastics industry and the textile industry.

The method is industrially feasible and safe, environmentally friendly and economically viable compared to other methods. The invention reduces the harmful evaporation of chemicals and at the same time improves the residues of the polymerizable substances used, for example, in the treatment of wood materials, by about 2 to 3 times that of an open and weightless system. From an economic point of view, the invention can be considered to save chemical costs by an average of 100 to 200 kg / m 3 compared to open polymerization systems. Correspondingly, the invention makes it possible to reduce the production costs of manufacture from 20 to 50%, depending on the species, on average 25 to 35%. Thus, the same combination of hardness or other properties is achieved with 20 to 35% less solution volumes compared to open production systems. In addition, the invention smoothes the amount of residues bound to different species of wood, and the areas of the species that are not homogeneously treated are not so clearly distinguished.

Claims (9)

1. A process developed to improve the properties of wood materials, characterized in that a wood object or its shingle to improve liquid permeability, ie. permeability has been pretreated prior to impregnation by disintegrating its cellular structure by treating the wood article or its woodwork by heating or mechanically and that the wood article or its woodwork may absorb a liquid synthetic polymerizable agent and that post-impregnation polymerization is carried out in the same space provided a dense barrier outside the wooden object between heat-regulating surfaces or by letting a tight space enclose the wooden object and the temperature-regulating surfaces. Process according to any of the preceding claims, characterized in that in the dense space, adjustable overpressure has been created by means of a medium, preferably gas, and an overall control of the process conditions by means of various types of media, preferably liquid, meadow, gas or straining, and that heat generated by an exothermic polymerization reaction is removed by reducing the overpressure or by changing it, the temperature of the process is regulated and at the same time the properties of the wood material are regulated in particular by the process conditions and the polymerizable agents remain in the wood by changing various types. media and their quantities. Method according to any of the preceding claims, characterized in that a wood object or its wood for improving liquid permeability is pre-treated by partially decomposing its cellular structure with cock, knife or laser preferably before processing or thereafter or preferably, or preferably cutting and turning in connection with machining. Process according to any one of the preceding claims, characterized in that a wooden object or its wood for specially improving liquid permeability is pre-treated before impregnation by heating, preferably by means of hot water, meadow or hot gas, before processing or thereafter. Process according to any of the preceding claims, characterized in that pre-treatment by heating is carried out before processing or thereafter by pouring the wooden object or its timber at an elevated temperature of 70-250 ° C, preferably when exposed to heat at a temperature of 80 -90 ° C 15-30 hours, preferably 10-15 hours, when exposed to heat or pretreatment at the highest temperatures of 90-250 ° C shortens the treatment time in a corresponding manner. Method according to any of the preceding claims, characterized in that the planar or shaped wooden article has been designed according to its anistropic cutting direction so that the number of ring rings radially visible in its surface is as large as possible to improve the permeability and properties of the wood. A method according to any of the claims wherein polymerization of a wood impregnated with a polymerizable agent is carried out between heat-regulating surfaces which are the surfaces of elements made of a material which conducts heat well, which elements are made of metal, characterized in that channels in which conducts heat and a medium which regulates the process and properties of the wood has been arranged in the elements, which have been produced in a material which conducts heat well. Method according to any of the preceding claims, characterized in that a dense space is provided by, for example, placing outside the wooden object between the heat-regulating surfaces a dense barrier whose material has been selected, for example, from metal, rubber, wood, glass, plastic or a combination of these. . Method according to any of the preceding claims, characterized in that the heat-conducting clamping surfaces which pour the wooden articles tightly and in a stack separately in their shape follow the surfaces of the polymerizable wooden article according to the shape of the article, the shape of the outer surface of the article being preferably flat, curved. or three-dimensional curved.